DSP Shape Factor and Weak Signals

[Bill W4ZV]

         This is a little related to the previous CW Pitch discussion.
I sometimes also like a wide bandwidth and/or wide shape factor
when listening to weak signals.  Orion's DSP had the ability to
change the DSP filter tap settings which had the effect of widening
the shape factor.  I notice the same effect has been mentioned by
the Flex Radio guys.  See the Thread titled "[Flexradio] Lower DSP
Buffer for SSB Receiving Weak Sigs" below:

http://www.mail-archive.com/flexradio@.../

         Question for Lyle or whoever might know...does the K3 DSP
allow for easy adjustment of the tap setting?  If so, can this be
adjusted from the front panel with one of the PF keys?

                                 73,  Bill  W4ZV

   

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[KK7P]

> Question for Lyle or whoever might know...does the K3 DSP
> allow for easy adjustment of the tap setting?  

There are several ways to get this effect.  Altering the tap settings
may be one way.

The K3 initial firmware provides two features that may be used to
achieve a similar effect.

The first is to set the wider bandwidth using the WIDTH control, then
turn on NR (noise reduction).  If the band is quiet, this will result in
suppression of noise.  When a signal appears, NR essentially builds a
low tap count filter around it, so you get much of the effect you're
referring to.  Of course, the narrower the WIDTH setting, the less
effect NR will have.

If the band is crowded, you can use the dual passband feature (sometimes
referred to as focus and context filtering) to emphasize the signal near
the sidetone pitch you prefer while still allowing you to hear - at
reduced gain - nearby frequencies.

73,

Lyle KK7P


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